The Leamington History Group runs walking tours of Leamington from April to October. Most are run by volunteers and are free! The walk which many people start with is A Walk Back in Time, led by David Morse. I managed to keep him stationary just long enough for him to tell me about the walk, some of its highlights and how you can book.
https://www.eventbrite.co.uk/o/leamington-history-group-68599114813
